1. Technical Field
The present invention relates to an exposure device that is provided with a plurality of light sources and also to an image forming apparatus that uses the exposure device.
2. Related Art
In an existing art, it has been proposed that an electrophotographic image forming apparatus that uses an exposure device, in which a plurality of light emitting elements are arranged, for exposing an image carrier such as a photoreceptor drum. A configuration in which microlenses are arranged to be opposed to groups (hereinafter, referred to as “element groups”) into which a plurality of light emitting elements are separated in units of the predetermined number of elements, which is described in JP-A-2000-15875 and JP-A-2001-205845. Light emitted from the predetermined number of light emitting elements that belong to one of the element groups is collected by the microlens corresponding to the element group to form an image on the surface of the image carrier.
Meanwhile, a positional relationship (for example, a distance) between each of the light emitting elements that belong to one of the element groups and the optical axis of the corresponding microlens varies every light emitting element in the group. For this reason, the size of a region that light emitted from each light emitting element reaches on the surface of the image carrier (hereinafter, referred to as “spot region”) and/or the intensity of energy applied to the spot region vary every light emitting element due to various conditions such as an aberration of microlens. Thus, there is a problem that an image formed with the image forming apparatus may have non-uniformity in resolution and/or gray-scale level.